Stem Cells Harvested From Cadavers

By Janet McConnaughey

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By Janet McConnaughey

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Scientists have coaxed new life out of dead
brains.

It turns out that even cadavers can supply the incredibly
versatile brain stem cells — master cells which can turn into
different kinds of brain and nerve cells — once thought available
only from fetal tissue.

So can skin. And it appears that just about every bone stem cell
can be tweaked to produce brain cells.

“It’s an extraordinarily exciting field,” said Ronald D.G.
McKay of the National Institute of Neurological Disorders and
Stroke.

Ethical Dilemma of Fetal Tissue

Several reports to the Society for Neuroscience seem to offer
yet more possible solutions to the ethical dilemma blocking stem
cell studies which use human fetal tissue.

But they are not yet solutions and may never be, said McKay and
two other scientists who discussed their findings at a news
conference Sunday at the society’s annual meeting.

There are big differences among stem cells from embryos, from
fetuses and from adult tissue, and scientists don’t really know
much yet about any of them, they said.

“We can’t look in a dish at a mixed population [of cells] and
say ‘That is a stem cell,’” said Fred H. Gage of the Salk
Institute at LaJolla, Calif., where the cadaver work was done.
“Different people have different ideas.”

The main definitions, said Ira Black of the University of
Medicine and Dentistry of New Jersey, are that stem cells are
immature cells which can duplicate themselves and grow into
different kinds of mature cells.

Gage’s research used bits of tissue taken soon after death from
children and young adults who had died of various neurological
diseases.

Cells Are Good for Days

His lab got the tissue 10 hours to three days after death. In
every case — as well as with cells from a man who died at 72 — researcher Theo Palmer was able to get some of the cells to divide
and reproduce themselves, and to grow into different kinds of
nervous system cells, Gage said.

Black grew brain cells from cells taken from bone marrow, where
they ordinarily would have created bone, cartilage, muscle, tendon
and fat cells.

He previously reported that he and his colleagues had been able
to turn 80 percent of the bone marrow cells taken from rats and
humans into nerve cells. Additional work has brought that up to
more than 99 percent, he said.

Freda Miller of McGill University had been scheduled to discuss
her work turning rat skin and human scalp cells to nerve cells but
could not make it.

“That’s yet another extraordinary finding,” Black said.

“It may be that there is a variety of easily accessible sources
that can generate neurons,” he said. If that’s the case, he said,
scientists will need to find out what they all have in common.

Researchers have transplanted dopamine-producing cells derived
from fetal tissue into peoples’ brains. But there is enough for
only a few of the estimated 1.2 million sufferers, and research has
been slowed by restrictions on the use of federal money for studies
involving fetal tissue.

“If you’re going to use this as a routine therapy, you need
access to large numbers of cells,” McKay said.

McKay said his laboratory has produced unlimited numbers of
dopamine neurons — but they produce high levels of dopamine only
for a short time.

“We need to know what kind of signals to give them” to get the
best production, he said.